1. Technical Field
The present invention relates to a lens grinder and a method of grinding a lens.
2. Prior Art
Lens grinders are known such as shown in Japanese Utility Model Publication No. 51-47669/1976, Japanese Patent Disclosure No. 62-152664 1987 and No. 59-192449/1984.
The above mentioned lens grinder disclosed in the first and second documents performs curve genrator grinding and fillet grinding working. The lens grinder of the first document includes a fillet spindle upward from and 45 degrees to the optical functional surface curve genrator. The fillet spindle is movable in an axial direction and also parallel to and perpendicular to the axis of the curve generator. The lens grinder of the second document does not add specific device and the lens to be worked and the optical functional surface grinding stone are suitably relatively moved to perform curve generator work and fillet grinding work.
Whereas, the lens grinder described in the third document performs the curve genrator grinding and outer periphery grinding by adding an outer periphery grinding stone outward from the curve generator grinding stone.
However, the lens grinder described in the first and second documents can perform the curve generator grinding and the fillet grinding sequentially, bu the outer periphery grinding must be another process. The lens grinder described in the third document can perform the curve generator grinding and the outer periphery grinding sequentially, but the fillet grinding must be other process. Thus, the known lens grinder can perform the curve generator grinding and one of the fillet grinding and the outer periphery grinding of the lens sequentially or simultaneously, however, the three processes of the curve generator grinding, fillet grinding and outer periphery grinding can not be performed simultaneously or sequentially.
Thus, whether the two processes are performed simultaneously or sequentially, the remaining fillet grinding or outer periphery grinding must be performed afterward so that working process is not decreased, and also the grinding of highly accurate centering of a lens especially one having a small Z value and difficult to centering working.